title: Blood pressure-renal blood flow relationships in conscious angiotensin II- and phenylephrine-infused rats.
abstract: Chronic ANG II infusion in rodents is widely used as an experimental model of hypertension, yet very limited data are available describing the resulting blood pressure-renal blood flow (BP-RBF) relationships in conscious rats. Accordingly, male Sprague-Dawley rats (n = 19) were instrumented for chronic measurements of BP (radiotelemetry) and RBF (Transonic Systems, Ithaca, NY). One week later, two or three separate 2-h recordings of BP and RBF were obtained in conscious rats at 24-h intervals, in addition to separate 24-h BP recordings. Rats were then administered either ANG II (n = 11, 125 ng·kg(-1)·min(-1)) or phenylephrine (PE; n = 8, 50 mg·kg(-1)·day(-1)) as a control, ANG II-independent, pressor agent. Three days later the BP-RBF and 24-h BP recordings were repeated over several days. Despite similar increases in BP, PE led to significantly greater BP lability at the heart beat and very low frequency bandwidths. Conversely, ANG II, but not PE, caused significant renal vasoconstriction (a 62% increase in renal vascular resistance and a 21% decrease in RBF) and increased variability in BP-RBF relationships. Transfer function analysis of BP (input) and RBF (output) were consistent with a significant potentiation of the renal myogenic mechanism during ANG II administration, likely contributing, in part, to the exaggerated reductions in RBF during periods of BP elevations. We conclude that relatively equipressor doses of ANG II and PE lead to greatly different ambient BP profiles and effects on the renal vasculature when assessed in conscious rats. These data may have important implications regarding the pathogenesis of hypertension-induced injury in these models of hypertension.
authors.affiliation: Correspondence: A. K. Bidani, Loyola Univ. Medical Center, 2160 South First Ave., Maywood, IL 60153. abidani@lumc.edu.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Polichnowski
authors.forename: Karen A
authors.initials: KA
authors.lastname: Griffin
authors.forename: Jianrui
authors.initials: J
authors.lastname: Long
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Williamson
authors.forename: Anil K
authors.initials: AK
authors.lastname: Bidani
mesh_terms: D000804:Angiotensin II / Q000008:administration & dosage* / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D003243:Consciousness; D004195:Disease Models, Animal; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced*; D007262:Infusions, Intravenous; D008297:Male; D010656:Phenylephrine / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000187:drug effects*; D013686:Telemetry; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D010656:Phenylephrine
keywords: blood pressure variability; hemodynamics; hypertension